The Problem
Placing fences and water pumped from boreholes was well meant and served its purpose, but it is most likely at the root of today’s so-called ‘elephant problem’ in several of our protected areas. Although not fenced, the Hwange National Park in Zimbabwe and the Khaudum Game Reserve in Namibia are swamped with artificial water. In the past, these areas served as wet season ranges, and only a few elephants stayed here during the dry season. Here, as in Kruger, many elephants have become year-round residents.
For the past 20 years, numbers in Etosha have remained at around 2,500 for no reason other than that about five per cent of elephants die yearly, many from the naturally occurring anthrax. A population of 2,500 is many more than the 50 living in Etosha during the 1950s. Unsurprisingly, the woody plants fell victim to the unaccustomed and continuous presence of many elephants. Now, nearly 20 per cent of the land surface of Etosha within four kilometres of water holes is losing woody plants at rates well beyond replacement values. Depletion of food close to water may be a further factor as this forces breeding herds to forage further afield.
In Kruger, 27 years of elephant culling went hand in hand with the increasing placement of boreholes and dams. By the time culling ended in 1994/95, there were 365 artificial water holes outside the rest camps. Every elephant had to walk at most five kilometres to find water over about 80 per cent of the land surface of the park. The population responded well, and elephant numbers in Kruger increased at near-maximal rates, albeit that culling also contributed to the high growth rate. From a retrospective assessment for Kruger, we know that growth rates during the years of culling were nearly double the value recorded some 10 years afterwards. Intensive culling reduces numbers but not population growth. This population increased faster after the final fencing of the park than before. Two factors drove elephant numbers in Kruger: water provisioning and the park’s fencing.
These have jointly neutralised the limiting effects of droughts and downgraded the role of regional movements as population reducers and mediators of impact. More important, however, is the effect water distribution has had on plants in Kruger. For instance, water provisioning also allowed grass-eating antelope numbers to increase locally, resulting in over-grazing and bush encroachment. In concert with fire, this influences other species living in Kruger.
Elephants usually return to riverfronts at the end of the rains – that is when they are free to move and not enticed to stay on wet season ranges with watering points that people maintain. Plants respond to the seasonal ebb and flow of numbers as this provides an opportunity for recovery. As a result, plants on dry season ranges should be able to recover during the wet season when elephants roam elsewhere. The same holds for plants in the wet season ranges. Here, the grass that elephants feed on during the rains can recover its rooting system during the dry season, thereby enhancing leaf growth during the next wet season. Under such conditions, trees like marulas that typically grow on high-lying wet season ranges are also safe from elephants during the dry season. Space that provides for seasonal roaming is driven by season and therefore modulates local impact naturally. It makes more sense to manage movement as a moderator of impact instead of culling to cut back numbers.